6.2.4 Selections

List panels -- all choices, in fact -- can have selections, and you can set them from within Lisp. This is useful for providing default settings in a choice, or when a user selection has an effect on other settings than just the one they made.

The selection is represented as a vector of offsets into the list of the choice's items, unless it is a single-selection choice, in which case it is just represented as an offset.

The initial selection is controlled with the initarg
:selection. The accessor
choice-selection
is provided.